The purpose of these experiments is to quantitate the combined effects of normal aging processes and ethanol treatment, as they are expressed in metric parameters and spine densities of Purkinje cell dendritic networks. Network analysis of dendritic arborization will be used to analyze Purkinje neurons of male Fischer 344 rats. Ethanol in a nutritionally adequate liquid diet will be administered for six- and twelve-month-periods beginning at 12 months of age. The analytic procedures will define quantitative changes at termination of each ethanol treatment and following a two-month recovery period after termination. Decreases in mean values of terminal segment lengths, total length of terminal segments, and total length of the network will be used to identify regression in these neurons. Terminal branches in each network (which account for over 50% of the branches and length of each network) will be categorized according to the type of junction they form with internal branches. Changes in frequency distributions of segment lengths contributing to these junctions will localize sites of change due to ethanol and/or aging within the networks. Determinations of spine density on terminal branches will measure the stability of synaptic input to these neurons.